Cells

Question 1

What are the main features of a prokaryotic cell

Answer 1

1. No membrane bound nucleus or organelles
2. Smaller than eukaryotic cells

Question 2

Structure and function of cell wall in prokaryotes

Answer 2

Made of of murin, maintains shape of cell and allows exchange of materials from the outside

Question 3

Structure and function of slimy capsule in prokaryotes

Answer 3

Gelatinous layer, prevents cell drying out and important in adhesions

Question 4

Structure and function of cell membrane in prokaryotes

Answer 4

Contains less phospholipids the eukaryotic cell membranes, selectively permeable so controls what enters + leaves cell

Question 5

Structure and function of plasmids in prokaryotes

Answer 5

Small circular, double stranded dna molecules in cytoplasm, passed from one bacterial cell to another when they exchange genes

Question 6

Structure and function of flagellum in prokaryotes

Answer 6

Composed of tublin, used to move cells

Question 7

Structure and function of ribosomes in prokaryotes

Answer 7

Smaller than eukaryotic ribosomes (70s), site of protein synthesis

Question 8

Structure and function of cytoplasm in prokaryotes

Answer 8

Contains dissolved substances, cytoskeleton present

Question 9

Structure and function of nucleus in eukaryotes

Answer 9

Surrounded by double membrane (nuclear envelope- has nuclear pores + joins to er), contains nearly all cells genetic material + controls protein synthesis

Question 10

Structure and function of nucleolus in eukaryotes

Answer 10

Dense spherical structure inside nucleus, not surrounded by a membrane, makes RNA and ribosomes

Question 11

Structure and function of ribosomes in eukaryotes

Answer 11

2 subunits(rRNA and protein), dense(80s), site of protein synthesis and acts as an assembly line where MRNA is used to assemble proteins from amino acids

Question 12

Structure and function of rough endoplasmic reticulum in eukaryotes

Answer 12

Complex system of membranes cause cisternae, covered in ribosomes, modifies proteins produced in ribosomes + transported in sacs

Question 13

Structure and function of smooth endoplasmic reticulum in eukaryotes

Answer 13

Not covered in ribosomes, steroid synthesis, lipid synthesis + makes hormones

Question 14

Structure and function of Golgi apparatus in eukaryotes

Answer 14

Stack of flattened sacks, had vesicles, Golgi vesicles transport molecules to different parts of the cell or outside, processes + sorts molecules from vesicles

Question 15

Structure and function of mitochondria in eukaryotes

Answer 15

Contain own dna(plasmid) and ribosomes, has a double membrane, converts energy from food so cell can use it, contains enzymes for respiration

Question 16

Structure and function of chloroplasts in eukaryotes

Answer 16

Double membraned, has plasmid dna, chlorophyll is found in grana, carries out photosynthesis (manufactures ATP)

Question 17

Structure and function of lysosomes in eukaryotes

Answer 17

Spherical sacs containing enzymes, has a membrane which keep’s enzymes separate( prevents digestion of useful structures), break down unwanted cells

Question 18

Structure and function of cell wall in eukaryotes

Answer 18

Made of cellulose,rigid, supports cell and prevents them from changing shape

Question 19

Structure and function of vacuole in eukaryotes

Answer 19

Filled with cell sap, maintains turgidity + rigidity of cell by storing water and exerting turgid pressure against cell wall

Question 20

Structure and function of cell surface membrane in eukaryotes

Answer 20

Provides structure to the cell + controls exchange of materials across it, made up of phospholipid bilayer

Question 21

What is the function of a capsid in a viral cell

Answer 21

Protein coat that encloses and protects RNA, in non-enveloped viruses it facilitates the attachment and penetration of virus to the host cell

Question 22

What is the function of the genetic material in viral cells

Answer 22

Codes for viral proteins

Question 23

What is the function of attachment proteins in viral cells

Answer 23

Unlocks host cell by interacting with ‘lock’ receptor on the cell surface (attachment/entry to host cell)

Question 24

What is the function of the lipid envelope in viral cells

Answer 24

Protects the capsid/genetic material

Question 25

What is the source of image for a light microscope, TEM and SEM

Answer 25

1. Light 2. Electrons 3. Electrons

Question 26

How is the beam focussed in light microscopes, TEM, SEM

Answer 26

1. Glass lens 2. A condenser electromagnet 3. A condenser electromagnet

Question 27

What is the max. effective mag. of a light microscope, TEM, SEM

Answer 27

1. x2000 2. Larger than l.m 3. Larger then l.m

Question 28

What is the max resolution of a light microscope, TEM, SEM

Answer 28

1. 200nm 2. Higher than l.m 3. Higher than l.m

Question 29

Can a live specimen be used in a light microscope, TEM, SEM

Answer 29

1. Yes 2. No 3. No

Question 30

Section of external of specimen in light microscope, TEM, SEM

Answer 30

1. Section 2. Section 3. External (3d)

Question 31

What is the cost of a light microscope, TEM, SEM

Answer 31

1. Cheaper than TEM, SEM 2. more expensive then l.m

Question 32

Can the image be viewed directly from a light microscope, TEM, SEM

Answer 32

1. Yes 2. No - on screen 3. No - on screen

Question 33

Is staining the specimen required for a light microscope, TEM, SEM

Answer 33

1. don’t have to 2. Yes (complex preparation) 3. Yes (complex preparation)

Question 34

What is magnification

Answer 34

How much bigger an object appears to be

Question 35

What is resolution

Answer 35

The ability to distinguish between 2 separate points

Question 36

Why is the max mag of a l.m x2000 when can produce higher mag

Answer 36

The resolution limits max useful magnification

Question 37

Formula for magnification

Answer 37

Mag =image size/actual size

Question 38

Steps of cell fractionation

Answer 38

1. Cut tissue + put into cold, isotonic, buffered solution (reduce enzyme activity, keeps same water potential to prevent organelles shrinking, prevents ph change so enzymes don’t denature) 2. Homogeniser releases organelles from cell 3. Filter homogenate to remove complete cells/large debris 4. Put it in centrifuge (slower speed the large fragments collect at bottom + smaller ones suspended in the supernatent and remove cell debri 5. Remove large fragments and respin the supernatent at higher speed